<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- 求数组【2.6.1.7，4]里面所有元素的和以及平均值 -->
    <script>
        var arr = [2.6, 1.7, 4];
        var sum = 0;
        for(var i = 0; i < arr.length; i++) {
            sum += arr[i];
        }
        var avg = sum / arr.length;
        console.log("数组[" + arr + "]里面所有元素的和为：" + sum);
        console.log("数组[" + arr + "]里面所有元素的平均值为：" + avg);
    </script>
</body>
</html>